Vehicle self-diagnostic device

Abstract

To provide a vehicle self-diagnostic device capable of notifying when a vehicle speed of an own vehicle which is acquired based on a rotation speed per unit time of a wheel of the own vehicle, is inaccurate.SOLUTION: A vehicle self-diagnostic device comprises: a camera 22 which outputs information on an image obtained by photographing a predetermined region around an own vehicle; a millimeter-wave radar 23 which acquires and outputs a relative speed which is a speed of a three-dimensional object with respect to the own vehicle; and a vehicle speed sensor 21 which acquires and outputs a vehicle speed of the own vehicle based on a rotation speed N per unit time of a wheel of the own vehicle. The vehicle self-diagnostic device is configured to: identify a static object OB around the own vehicle based on the information output from the camera 22; acquire a relative speed vr which is a speed of the static object OB with respect to the own vehicle from the millimeter-wave radar 23; acquire an absolute value of a component in a direction parallel to a travel direction of the own vehicle as an actual speed vsa of the own vehicle; and provide a driver with predetermined information when duration of a state where the absolute value of a difference between the vehicle speed vs from the vehicle speed sensor 21 and the actual vehicle speed vsa exceeds a threshold exceeds a threshold.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a vehicle self-diagnosis device capable of reporting that the vehicle speed (absolute value) of the vehicle, which is acquired based on the number of rotations per unit time of the wheels of the vehicle, is inaccurate. [Background technology]

[0002] A vehicle speed sensor that detects the vehicle speed of the vehicle itself is well known (see, for example, Patent Document 1 below). This type of vehicle speed sensor acquires the number of rotations N of the wheel per unit time, and multiplies the number of rotations N by the dynamic load radius (coefficient k) of the wheel to acquire and output the vehicle speed vs of the vehicle itself. This coefficient k is determined when the vehicle is shipped from the factory (when the vehicle is designed), and is stored in a storage device (ROM) of the vehicle speed sensor. In other words, the coefficient k is a fixed value (cannot be rewritten). In addition, in conventional vehicles, the value (vehicle speed vs) output from the vehicle speed sensor may be displayed on a display (speedometer) provided on the instrument panel of the vehicle. In addition, the vehicle itself may be controlled (driving assistance, automatic driving) based on the value (vehicle speed vs) output from the vehicle speed sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-236570 A Summary of the Invention

[0004] Incidentally, the dynamic loaded radius of a wheel changes (expands or contracts) depending on the tire air pressure. In addition, when a user replaces the wheels of the vehicle, the dynamic loaded radius may change. For example, if the outer diameter of the replaced wheels is larger than the outer diameter of the wheels when the vehicle was shipped from the factory (if the wheels are increased in size), the dynamic loaded radius is likely to increase. However, as described above, the coefficient k of the vehicle speed sensor is a fixed value. Therefore, due to the change in the dynamic loaded radius of the wheel, the difference (error) between the vehicle speed vs output from the vehicle speed sensor and the actual vehicle speed vsa may become relatively large.

[0005] An object of the present invention is to provide a vehicle self-diagnosis device capable of reporting that the vehicle speed obtained based on the number of rotations per unit time of the wheels of the vehicle is inaccurate.

[0006] In order to solve the above problems, the present invention provides a vehicle self-diagnosis device (1), A camera (22) that captures an image of a predetermined area around the vehicle and outputs information related to the image. A millimeter wave radar (23) that acquires and outputs a relative speed of a three-dimensional object relative to the vehicle; a vehicle speed sensor (21) that acquires and outputs a vehicle speed (vs) of the host vehicle based on the number of rotations per unit time (N) of the wheels of the host vehicle; a processor (10) for identifying a stationary object (OB) around the vehicle based on information acquired from the camera, acquiring from the millimeter wave radar a relative speed (vr) of the stationary object relative to the vehicle, acquiring an absolute value of a component of the relative speed of the stationary object in a direction parallel to the traveling direction of the vehicle as an actual vehicle speed (vsa) of the vehicle, acquiring the vehicle speed from the vehicle speed sensor, and controlling an alarm device (30) so that predetermined information is provided to a driver when a duration (Δt) of a state in which an absolute value (Δvs) of a difference between the vehicle speed and the actual vehicle speed exceeds a threshold value (Δvsth) exceeds a threshold value (Δtth); Equipped with.

[0007] In this specification, "velocity" is a concept (vector) that includes the direction in which an object travels and its speed (absolute value). On the other hand, "vehicle speed" and "actual vehicle speed" are concepts (scalars) that mean the speed (absolute value) of a vehicle and do not include the direction in which the vehicle travels.

[0008] The absolute value (speed) of the component of the relative speed (vector) between a three-dimensional object (stationary object) fixed on the ground and the vehicle, which is parallel to the traveling direction of the vehicle, coincides with the actual vehicle speed (absolute value) of the vehicle. The processor of the vehicle self-diagnosis device according to the present invention identifies a stationary object based on information acquired from a camera, and acquires the absolute value of the component of the relative speed (vector) that is the speed of the stationary object as seen from the vehicle, which is parallel to the traveling direction of the vehicle, as the actual vehicle speed of the vehicle based on information acquired from a millimeter wave radar. This allows the processor to acquire the actual vehicle speed of the vehicle with high accuracy using a means other than the vehicle speed sensor. If the duration of a state in which the absolute value of the difference between the vehicle speed acquired from the vehicle speed sensor and the actual vehicle speed exceeds a threshold value exceeds the threshold value, it is highly likely that the current value and the design value of the dynamic load radius of the wheel are excessively large or excessively small. In this case, the processor determines that the vehicle speed output from the vehicle speed sensor is inaccurate, and provides the driver with predetermined information (information indicating that the output of the vehicle speed sensor is inaccurate). As described above, the vehicle self-diagnosis device according to the present invention can detect that the vehicle speed of the host vehicle output from the vehicle speed sensor is inaccurate (has low reliability).

[0009] In one aspect of the present invention, there is provided a vehicle self-diagnosis device, When the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold value exceeds a threshold value, the processor executes a correction process to correct the vehicle speed output from the vehicle speed sensor based on the ratio of the actual vehicle speed to the vehicle speed obtained from the vehicle speed sensor.

[0010] This allows other ECUs in the vehicle (e.g., an ECU that performs driving assistance, an ECU that displays the vehicle speed on a display device provided on the instrument panel, etc.) to perform various processes based on the corrected vehicle speed (accurate value).

[0011] In another aspect of the present invention, there is provided a vehicle self-diagnosis device, The processor executes the correction process when the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold value exceeds the threshold value and when the driver of the vehicle performs an operation requesting correction of the vehicle speed.

[0012] This allows the driver to select whether or not to correct the vehicle speed output from the vehicle speed sensor.

[0013] In another aspect of the present invention, there is provided a vehicle self-diagnosis device, The processor controls the notification device so that, when the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold value exceeds a threshold value and the driver of the vehicle does not perform an operation requesting correction of the vehicle speed, the processor controls the notification device so that information regarding the wheels of the vehicle is provided to the driver without performing the correction process.

[0014] For example, the processor causes the display device to display information (images) related to how to measure and adjust the air pressure of the wheels and how to replace the wheels as information to encourage the user to inspect the wheels. The processor also causes the display device to display, for example, information related to repair shops that can replace the wheels of the vehicle. When the driver or a repair shop staff member adjusts the air pressure of the wheels (tires) or replaces the wheels, the dynamic load radius becomes approximately equal to the design value, and the vehicle speed sensor outputs an accurate vehicle speed.

[0015] In another aspect of the present invention, there is provided a vehicle self-diagnosis device, When the duration during which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold value exceeds the threshold value and the driver of the vehicle does not perform an operation requesting correction of the vehicle speed, the processor temporarily disables a driving assistance function of the vehicle without performing the correction process.

[0016] There are cases where a control device (driving assistance ECU) provided in a vehicle is configured to execute driving assistance based on a vehicle speed output from a vehicle speed sensor. In a vehicle designed in this way, if the vehicle speed output from the vehicle speed sensor is inaccurate, there is a risk that driving assistance will not be executed as intended by the designer. According to the present invention, if it is determined that the output of the vehicle speed sensor is inaccurate, execution of driving assistance is prohibited. In other words, it is possible to prevent driving assistance that is different from the designer's intention from being provided. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram of a vehicle self-diagnosis device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view showing a process of acquiring the actual vehicle speed. [Diagram 3] FIG. 3 is a flowchart of a program executed by the CPU to realize the correction function. [Figure 4] FIG. 4 is a flowchart of a program executed by the CPU to realize the diagnostic function and the correction coefficient updating function. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] (Summary) 1, a vehicle self-diagnosis device 1 according to one embodiment of the present invention is applied to a vehicle V (hereinafter referred to as "host vehicle") equipped with an automatic driving function. The vehicle self-diagnosis device 1 has a function (diagnosis function) of detecting and reporting that the host vehicle speed vs output from a vehicle speed sensor 21, which will be described later, is inaccurate, and a function (correction function) of correcting the vehicle speed vs when the vehicle speed vs is inaccurate.

[0019] (Specific configuration) As shown in FIG. 1, the vehicle self-diagnosis device 1 includes an ECU 10, an on-vehicle sensor 20, an alarm device 30, and an operation switch 40.

[0020] The ECU 10 is equipped with a microcomputer including a CPU 10a, a ROM 10b (a rewritable non-volatile memory), a RAM 10c, a timer 10d, etc. The CPU realizes various functions by executing programs (instructions) stored in the ROM. The ECU 10 is connected to other ECUs (e.g., an ECU that performs driving assistance, an ECU that displays various parameters (e.g., the vehicle speed, engine RPM, etc.) on a display device provided on an instrument panel) via a CAN (Controller Area Network).

[0021] The on-vehicle sensor 20 includes a vehicle speed sensor 21, a camera 22, and a millimeter wave radar 23.

[0022] The vehicle speed sensor 21 includes a rotation speed measurement circuit and a vehicle speed calculation device. The rotation speed measurement circuit includes a pulse generation circuit that outputs a pulse (electrical signal) every time the wheel of the vehicle rotates by a predetermined angle, and a counter circuit that counts the number of the pulses. The vehicle speed calculation device acquires the output value (number of pulses) of the counter circuit at a predetermined cycle (every time unit time elapses) and resets the count value to "0". In this way, the vehicle speed calculation device acquires the number of rotations N of the wheel per unit time. Then, the vehicle speed calculation device acquires the vehicle speed vs (absolute value) of the vehicle by multiplying the number of rotations N by a coefficient k. The coefficient k is stored in a ROM included in the vehicle speed calculation device. In other words, the coefficient k is a fixed value. The vehicle speed sensor 21 provides the vehicle speed vs to the ECU 10.

[0023] The camera 22 includes an imaging device and an image analysis device. The imaging device includes, for example, a CCD. The imaging device is installed in the front of the vehicle and is directed toward the front of the vehicle. The imaging device captures the foreground of the vehicle at a predetermined frame rate to obtain image data. The image analysis device obtains image data from the imaging device, analyzes the image data, recognizes (identifies) targets present within the viewing angle, and obtains the position (relative position) of the target with respect to the vehicle based on the position (coordinates) of the target in the image. For example, the image analysis device recognizes (identifies) a three-dimensional object (stationary object OB (e.g., a traffic sign)) installed (fixed) on the ground, and obtains its position P (position of the stationary object with respect to the vehicle). The image analysis device provides the recognition result (target identification result and position of the target with respect to the vehicle) to the ECU 10.

[0024] The millimeter wave radar 23 includes a transmitting / receiving unit and a signal processing unit (not shown). The transmitting / receiving unit radiates millimeter wave band radio waves (hereinafter referred to as "millimeter waves") forward of the vehicle and receives millimeter waves (reflected waves) reflected by a three-dimensional object located within the radiation range. The signal processing unit acquires various information regarding each reflection point R of the millimeter wave based on physical quantities such as the time from when the transmitting / receiving unit radiates the millimeter wave to when it receives the reflected wave, the attenuation level of the reflected wave, and the difference between the frequency of the radiated millimeter wave and the frequency of the received reflected wave. For example, the signal processing device calculates the position of each reflection point R (relative position RP (direction and distance) with respect to the transmitting / receiving unit). In addition, the signal processing unit calculates the relative speed vr (vector) that is the speed of each reflection point R with respect to the vehicle. Then, the calculation result (data indicating the distribution of the reflection points R (data including the position RP and relative speed vr of each reflection point R)) is transmitted to the ECU 10. The range in which the millimeter wave radar 23 can notify a three-dimensional object (the range in which millimeter waves are emitted) is substantially the same as the angle of view (imaging range) of the camera 22.

[0025] The notification device 30 includes an image display device and an audio device. The image display device receives an image display command from the ECU 10 and displays a predetermined image in response to the command. The audio device receives a sound playback command from the ECU 10 and plays a predetermined sound in response to the command.

[0026] The operation switch 40 includes a first switch 41 which is operated when the driver requests to start a vehicle speed diagnosis, which will be described later, and a second switch 42 which is operated when the driver requests to update the correction coefficient Δk. These switches are, for example, configured with a push button type switch device. These switches are, for example, incorporated in the spokes of the steering wheel. The ECU 10 monitors the on / off states of these switches.

[0027] (Correction function) When the ignition switch is on, the ECU 10 acquires the vehicle speed vs from the vehicle speed sensor 21 at a predetermined cycle, and provides the vehicle speed vs obtained by multiplying the vehicle speed vs by a correction coefficient Δk to other ECUs (for example, an ECU that executes driving assistance such as ACC (=adaptive cruise control), and an ECU that displays the vehicle speed on a display device of an instrument panel). Here, the correction coefficient Δk is initialized to "1" when the vehicle is collected from the factory (that is, when the dynamic load radius of the wheel is consistent with the design value or the error is small). As described later, the correction coefficient Δk is updated when a predetermined operation is executed. The correction coefficient Δk is stored in the ROM 10b (flash ROM). Therefore, even if the ignition switch is turned off, the correction coefficient Δk is held.

[0028] (Diagnostic function) When the ECU 10 detects that the first switch 41 is pressed, it acquires various information (information on the identified target and information on the reflection point R) from the camera 22 and the millimeter wave radar 23 at a predetermined cycle. Generally, an image analysis device of a camera can accurately identify each target (other vehicles, guard rails, signs, etc.) included in an image based on image data acquired from an imaging device. However, an image recognition device cannot accurately acquire the speed of each target (speed with respect to the vehicle (relative speed vr)). In contrast, a signal processing unit of a millimeter wave radar can accurately acquire the speed of each target (speed of the target with respect to the vehicle (relative speed vr)). However, the signal processing unit cannot accurately identify each target. In this embodiment, the ECU 10 identifies (selects) a stationary object OB based on information acquired from the camera 22, and acquires the speed (relative speed vr) of the stationary object OB with respect to the vehicle based on information acquired from the millimeter wave radar 23 (fusion processing).

[0029] Specifically, the ECU 10 associates a traffic sign (in this embodiment, a sign indicating a vehicle speed limit) as a stationary object OB (usually a predetermined type of target fixed on the ground) among the targets identified by the image recognition device of the camera 22 with a reflection point R corresponding to the stationary object OB. For example, the ECU 10 acquires a position P of the selected stationary object OB from the camera 22. Then, the ECU 10 selects, among the reflection points R acquired from the millimeter wave radar 23, a plurality of reflection points R that are at the same position as the position P (the position of the stationary object OB acquired from the image recognition device) or whose distance is equal to or less than a threshold value, and that are distributed so that a set of the reflection points (a group of reflection points) is substantially circular (the shape of a sign indicating a vehicle speed limit). Then, the ECU 10 selects a reflection point Rc located at the center of the selected plurality of reflection points R. The ECU 10 acquires a relative speed vr of the reflection point Rc from a signal processing device of the millimeter wave radar 23 (see FIG. 2). 2 is an XY coordinate plane with the origin O being the center of the front end of the vehicle in the vehicle width direction in a plan view, and the X axis is defined to coincide with the front-rear direction of the vehicle, and the Y axis is defined to coincide with the vehicle width direction of the vehicle. In the following description, the angle between the X axis and the straight line connecting the origin O and the reflection point Rc is referred to as "angle θ."

[0030] Here, the absolute value of the X-axis component of the relative speed vr coincides with the actual vehicle speed vsa of the host vehicle. The ECU 10 obtains the actual vehicle speed vsa based on the following calculation formula (1). vsa = |vr| × cosθ (1)

[0031] When the information acquired from the camera 22 includes information related to a plurality of stationary objects OB, the ECU 10 selects one of the stationary objects OB. For example, the ECU 10 selects the stationary object OB closest to the vehicle. However, the ECU 10 may select a plurality of stationary objects OB, calculate the actual vehicle speed vsa based on the relative speed vr of each stationary object OB, and use the average value of the plurality of actual vehicle speeds vsa as the actual vehicle speed vsa.

[0032] Next, the ECU 10 acquires the vehicle speed vs from the vehicle speed sensor 21. The ECU 10 calculates the absolute value (error Δvs) of the difference between the absolute value of the vehicle speed vs and the actual vehicle speed vsa. Next, the ECU 10 judges whether the error Δvs exceeds a threshold Δvsth. The ECU 10 uses the timer 10d to measure the time Δt during which the state in which the error Δvs exceeds the threshold Δvsth (Δvs>Δvsth) continues. If the time Δt exceeds the threshold Δtth, the ECU 10 judges that there is a high possibility that the current dynamic load radius of the wheel is excessively large or excessively small with respect to the design value. That is, the ECU 10 judges that the output of the vehicle speed sensor 21 is inaccurate. In this case, the ECU 10 causes the image display device of the notification device 30 to display an image indicating that "the vehicle speed vs is inaccurate" and causes the audio device to play a predetermined sound (beep sound).

[0033] On the other hand, when the error Δvs is equal to or smaller than the threshold Δvsth, the ECU 10 judges that the current dynamic loaded radius of the wheel is highly likely to match the design value. That is, the ECU 10 judges that the output of the vehicle speed sensor 21 is accurate. In this case, the ECU 10 causes the image display device of the notification device 30 to display an image indicating that "the output of the vehicle speed sensor is accurate" and causes the audio device to play a predetermined sound. Also, when the error Δvs becomes equal to or smaller than the threshold Δvsth before the time Δt reaches the threshold Δtth after the error Δvs exceeds the threshold Δvsth, it is highly likely that the dynamic loaded radius of the wheel has temporarily (for a short time only) fluctuated (increased or decreased from the design value). Therefore, in this case as well, the ECU 10 causes the notification device 30 to present information (image and sound) indicating that "the output of the vehicle speed sensor is accurate."

[0034] (Correction coefficient update function) After notifying that the output (vehicle speed vs) of the vehicle speed sensor 21 is inaccurate as described above, the ECU 10 causes the image display device to display an image used to execute an operation to approve updating the correction coefficient Δk, and causes the audio device to play a predetermined sound (update confirmation process). If the ECU 10 detects that the second switch 42 has been pressed within a predetermined time period after the time ts at which the ECU 10 executes the update confirmation process, the ECU 10 acquires (updates) the correction coefficient Δk based on the following calculation formula (2). Δk=vsa / vs (2)

[0035] If the second switch 42 is not pressed within a predetermined time after the time point ts, the ECU 10 disables a predetermined driving support function (a function for controlling the vehicle based on the vehicle speed vs) of the vehicle. In this case, the ECU 10 causes the image display device of the notification device 30 to display an image indicating that the predetermined driving support function has been disabled.

[0036] Next, a program PR1 executed by the CPU 10a (hereinafter simply referred to as "CPU") to realize the above correction function will be described with reference to Fig. 3. Also, a program PR2 executed by the CPU to realize the above diagnosis function and correction coefficient update function will be described with reference to Fig. 4.

[0037] (Program PR1) When the ignition switch is in the ON state, the CPU executes the program PR1 at a predetermined cycle. The CPU starts execution of the program PR1 from step 100 and proceeds to step 101.

[0038] In step 101, the CPU acquires the vehicle speed vs from the vehicle speed sensor 21. Next, the CPU advances the process to step .

[0039] In step 102, the CPU corrects the vehicle speed vs. That is, the CPU obtains an accurate vehicle speed vs. (corrected vehicle speed vs.) by multiplying the vehicle speed vs. by a correction coefficient Δk. Next, the CPU proceeds to step 103. The correction coefficient Δk is initialized to "1" at the time of shipment from the factory. As will be described later, the correction coefficient Δk may be updated after shipment from the factory when the CPU executes the program PR2.

[0040] The CPU provides the corrected vehicle speed vs to the other ECUs in step 103. Next, the CPU proceeds to step 104, where it ends the execution of the program PR1.

[0041] (Program PR2) When the CPU detects that the first switch 41 is pressed, the CPU starts the execution of the program PR2 from step 200 and causes the timer 10d to start measuring the time Δt.

[0042] In step 201, the CPU acquires the vehicle speed vs from the vehicle speed sensor 21. Next, the CPU advances the process to step 202.

[0043] In step 202, the CPU acquires the actual vehicle speed vsa (=|vr|×cos θ) based on various information acquired from the camera 22 and the millimeter wave radar 23. Next, the CPU proceeds to step 203.

[0044] In step 203, the CPU determines whether an error Δvs, which is the absolute value of the difference between the actual vehicle speed vsa and the vehicle speed vs, exceeds a threshold value Δvsth. If the CPU determines that the error Δvs exceeds the threshold value Δvsth (203: Yes), the CPU proceeds to step 204. On the other hand, if the CPU does not determine that the error Δvs exceeds the threshold value Δvsth (203: No), the CPU proceeds to step 206.

[0045] In step 204, the CPU determines whether or not the time Δt (the duration of the state in which the error Δvs exceeds the threshold Δvsth) exceeds the threshold Δtth. If the CPU determines that the time Δt exceeds the threshold Δtth (204: Yes), the CPU proceeds to step 205. On the other hand, if the CPU does not determine that the time Δt exceeds the threshold Δtth (204: No), the CPU returns to step 201.

[0046] In step 205, the CPU causes the image display device to display an image indicating that the vehicle speed vs output from the vehicle speed sensor 21 is inaccurate, and causes the audio device to play a predetermined sound. Next, the CPU proceeds to step 207.

[0047] In step 206, the CPU causes the display device to display an image indicating that the vehicle speed vs output from the vehicle speed sensor 21 is accurate, and causes the audio device to play a predetermined sound. Next, the CPU proceeds to step 210, where it ends the execution of the program PR2.

[0048] In step 207, the CPU causes the image display device to display an image used to execute an operation to start updating the correction coefficient Δk, and causes the audio device to play a predetermined sound, and then determines whether or not the second switch 42 is pressed within a predetermined time. If the CPU determines that the second switch 42 is pressed within the predetermined time (207: Yes), the CPU proceeds to step 208. On the other hand, if the CPU does not determine that the second switch 42 is pressed within the predetermined time (207: No), the CPU proceeds to step 209.

[0049] The CPU updates the correction coefficient Δk (= vsa / vs) in step 208. Then, the CPU proceeds to step 210 and ends the execution of the program PR2.

[0050] The CPU disables the predetermined driving assistance function (prohibits the execution of driving assistance) in step 209. Next, the CPU proceeds to step 210 and ends the execution of the program PR2.

[0051] (effect) The absolute value of the component of the relative speed (vector) between a three-dimensional object (stationary object OB) fixed on the ground and the host vehicle, which is parallel to the traveling direction of the host vehicle, corresponds to the actual vehicle speed of the host vehicle. The ECU 10 identifies the stationary object OB based on information acquired from the camera 22. The ECU 10 also acquires the relative speed vr between the stationary object OB and the host vehicle from the millimeter wave radar 23. The ECU 10 then acquires the absolute value of the X-axis component of the relative speed vr as the actual vehicle speed vsa of the host vehicle. This allows the ECU 10 to acquire the actual vehicle speed vsa of the host vehicle with high accuracy using a means other than the vehicle speed sensor 21. If the duration Δt of a state in which an error Δvs, which is the absolute value of the difference between the vehicle speed vs acquired from the vehicle speed sensor 21 and the actual vehicle speed vsa, exceeds a threshold Δvsth, exceeds a threshold Δtth, the ECU 10 determines that the current dynamic load radius of the wheel is likely to be excessively large or excessively small relative to the design value. That is, the ECU 10 determines that the vehicle speed vs output from the vehicle speed sensor 21 is inaccurate, and causes the notification device 30 to present predetermined information (information indicating that the output of the vehicle speed sensor 21 is inaccurate). As described above, the vehicle self-diagnosis device 1 can detect that the vehicle speed vs of the host vehicle output from the vehicle speed sensor 21 is inaccurate.

[0052] Furthermore, when the ECU 10 determines that the vehicle speed vs output from the vehicle speed sensor 21 is inaccurate and the driver requests updating of the correction coefficient Δk, the ECU 10 updates the correction coefficient Δk. After that, the ECU 10 corrects the vehicle speed vs acquired from the vehicle speed sensor 21 using the updated correction coefficient Δk. Then, the ECU 10 provides the corrected vehicle speed vs to other ECUs. The other ECUs included in the vehicle (for example, an ECU that performs driving assistance, an ECU that displays the vehicle speed on a display device provided on an instrument panel, etc.) can perform various processes based on the corrected vehicle speed vs (accurate value).

[0053] In addition, if the driving assistance ECU of the vehicle is configured to perform driving assistance (e.g., ACC) based on the vehicle speed vs output from the vehicle speed sensor 21, and if the vehicle speed vs output from the vehicle speed sensor 21 is inaccurate, there is a risk that the driving assistance (ACC) will not be performed as intended by the designer. The ECU 10 of the vehicle self-diagnosis device 1 according to this embodiment disables the driving assistance function (ACC) when it is determined that the vehicle speed vs output from the vehicle speed sensor 21 is inaccurate and when there is no request to update the correction coefficient Δk. This prevents the driving assistance (ACC) from being provided in a manner different from the designer's intention.

[0054] The present invention is not limited to the above-described embodiment, and various modifications can be adopted within the scope of the present invention, as described below.

[0055] <Variation 1> The vehicle self-diagnosis device 1 may have only the above-mentioned diagnostic function, and may omit the correction function and the correction coefficient update function.

[0056] <Variation 2> The vehicle self-diagnosis device 1 may include a device for detecting whether or not the wheels (tires) have been replaced. In this case, the ECU 10 may automatically start executing the program PR2 when it detects that the wheels have been replaced.

[0057] <Modification 3> When the ECU 10 determines that the vehicle speed vs is inaccurate, the ECU 10 may display on the display device an image used for the driver to select whether or not the wheels (tires) have been replaced. When the driver uses a predetermined operating device to select "the wheels (tires) have been replaced," the ECU 10 updates the correction coefficient Δk.

[0058] <Modification 4> When the second switch 42 is not pressed within a predetermined time from the time point ts, the ECU 10 may display information about the wheels on the display device. For example, when the vehicle speed vs is greater than the actual vehicle speed vsa, the ECU 10 displays an image on the image display device indicating that the air pressure of the wheels may be excessive. Conversely, when the vehicle speed vs is less than the actual vehicle speed vsa, the ECU 10 displays an image on the image display device indicating that the air pressure of the wheels may be insufficient. Also, for example, the ECU 10 displays information (images) on the display device regarding a method for measuring or adjusting the air pressure of the wheels and a method for replacing the wheels, as information for encouraging the user to check the wheels. Also, the ECU 10 may display information on a repair shop where the wheels of the vehicle can be replaced, for example, on the display device. When the driver or a person in the repair shop adjusts the air pressure of the wheels (tires) or replaces the wheels, the dynamic load radius approximately matches the design value, and the vehicle speed sensor 21 outputs an accurate vehicle speed vs. If the driving assistance function is disabled, after completing the above-mentioned wheel repair, the disabled driving assistance function is enabled by executing a specified operation (sending a specified command from an external device to ECU 10). [Explanation of symbols]

[0059] 1... vehicle self-diagnosis device, 10... ECU, 20... vehicle-mounted sensor, 30... notification device

Claims

1. a camera that captures an image of a predetermined area around the vehicle and outputs information related to the image; A millimeter wave radar that acquires and outputs the relative speed of a three-dimensional object relative to the vehicle; a vehicle speed sensor that acquires and outputs a vehicle speed of the host vehicle based on the number of rotations per unit time of the wheels of the host vehicle; a processor that identifies stationary objects around the vehicle based on information acquired from the camera, acquires from the millimeter wave radar a relative speed of the stationary object relative to the vehicle, acquires an absolute value of a component of the relative speed of the stationary object in a direction parallel to the traveling direction of the vehicle as an actual vehicle speed of the vehicle, acquires the vehicle speed from the vehicle speed sensor, and controls a notification device to provide predetermined information to a driver when a duration of a state in which the absolute value of a difference between the vehicle speed and the actual vehicle speed exceeds a threshold exceeds a threshold; A vehicle self-diagnosis device comprising:

2. 2. The vehicle self-diagnosis device according to claim 1, The processor executes a correction process to correct the vehicle speed output from the vehicle speed sensor based on the ratio of the actual vehicle speed to the vehicle speed obtained from the vehicle speed sensor when the duration of a state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold value exceeds a threshold value.

3. 3. The vehicle self-diagnosis device according to claim 2, The processor executes the correction process when the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold value exceeds the threshold value and the driver of the vehicle performs an operation requesting correction of the vehicle speed.

4. 3. The vehicle self-diagnosis device according to claim 2, The processor controls the notification device so that information regarding the wheels of the vehicle is provided to the driver without performing the correction process when the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold value exceeds the threshold value and the driver of the vehicle does not perform an operation requesting correction of the vehicle speed.

5. 3. The vehicle self-diagnosis device according to claim 2, The processor is a vehicle self-diagnosis device that, when the duration of a state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold value exceeds the threshold value and the driver of the vehicle does not perform an operation requesting correction of the vehicle speed, temporarily disables a driving assistance function equipped in the vehicle without performing the correction process.

Images